A systematic review of quality of life and health-related quality of life as outcome measures in substance and behavioural addictions

The assessment and treatment of substance-related and addictive disorders can benefit from a holistic consideration of an individual’s quality of life (QoL), however, there remains uncertainty over how the construct is operationalised as an outcome measure. The current systematic review aimed to identify all the QoL and health-related quality of life (HRQoL) instruments adopted as outcome measures in addiction research and map the conceptualised domains. Available psychometric evidence supporting their use was also summarised. A systematic search of three electronic databases and a specialised assessment library was conducted for studies utilising a QoL or HRQoL instrument as an outcome measure. Participants using or taking part at risky levels and above assessed with a valid measure were included. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidance was followed and included outcome instruments were appraised using mixed-methods. Validation studies were assessed for their risk of bias based on the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) risk of bias tool. Two hundred and thirty articles containing 258 discrete studies were included. Forty-seven outcome instruments were used: 28 assessing QoL in 141 studies; 19 assessing HRQoL in 117 studies. The WHOQOL-BREF was the most popular instrument utilised in 73 studies. Content analysis identified 39 unique domains of QoL. Eighteen articles comprising 20 validation studies evaluated the psychometric properties of 11 outcome measures. No instrument was assessed for the same parameter in 5 or more studies for meta-analytic pooling purposes. The ALQoLS, ALQoL-9, Q-LES-Q-SF, SF-36, and WHOQoL-BREF all produced multiple, promising internal consistency statistics (Cronbach’s α = 0.75–0.97), but with varying degrees of methodological quality. Other parameters of reliability and validity are also reported. It is clear many QoL and HRQoL instruments have been utilised in the field. However, a significant portion of studies applied a small number of popular instruments for which there is minimal high-quality validation evidence provided to support their use with populations at risk of addiction. There is a need for more rigorous primary studies with validation evidence presented for the appropriateness of the QoL or HRQoL assessment instrument chosen.